9 May 2015

Water Voles - signs and tracks

A Scottish water vole at Glen Callater
The Water Vole (Arvicola terrestris) is a herbivorous rodent that inhabits the banks of small running waters. You usually do not see the animal themselves but the signs of them are easy to spot and record! Sometimes you can hear them 'plop' into the water as you approach. They are not so common as they used to be due to habitat loss and predation by mink.

In Scotland, there should be no need for a licence to carry out a basic survey for water voles providing that you take reasonable precaution to avoid intentionally or recklessly disturbing these animals in their burrows, or possibly damaging their burrows (from the SNH webpage). Poking things into the holes (including your hand) could be considered disturbance.

Water voles are about 14-22 cm long and weigh 150-300 grams. They have a tapering tail like a rat. Water voles in Scotland appear to have a different genetic background to the ones in England and are also commonly much darker brown in colour, sometimes black. They dig burrows in soft banking along running water and they then collect rushes and grasses which they feed on, leaving a distinct 45 degree cut (very clean, not ragged). Like many small mammals they create latrines, i.e. they deposit their poop in specific places. The droppings are about the size and shape of a Tic Tac and green/dark green in colour. Usually they like waters less than 3m in width and 1m deep, but are also found in the highlands in very small watercourses. They like a steep bank that's easy to burrow into and a plentiful supply of soft rushes and sedges along the edge of the water. 

Signs of other small mammals can easily be confused with those of the water vole, namely the brown rat (of similar size so can be very confusing) and other voles (much smaller burrow entrances and poop). The most distinct sign there is a water vole around is the presence of their very green, Tic Tac sized/shaped poop!

Below are some signs to look out for if you find yourself in suitable habitat:

Note the surgically cut rushes, and some little poops too!

Holes are usually wider than they are high, about 4-8cm.
You may find clippings of food near the entrance.

Spot the droppings! The latrines are usually made on bare earth/mud.
You can read more about the water vole here!